Electrocatalytic CO2 reduction(CO2 ER)into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals,however,it still suffers from limited catalytic activity and poor selectivity...Electrocatalytic CO2 reduction(CO2 ER)into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals,however,it still suffers from limited catalytic activity and poor selectivity.Herein,we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles(NPs)supported on nitrogen-doped reduced graphene oxide(Bi/Bi2 O3/NrGO)nanosheets prepared by a combined hydrothermal with calcination treatment.Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi2 O3,Bi/Bi2 O3/NrGO-700 hybrid displays a promoted CO2 ER catalytic performance and selectivity for formate production,as featured by a small onset potential of-0.5 V,a high current density of-18 mA/cm2,the maximum Faradaic efficiency of85%at-0.9 V,and a low Tafel slope of 166 mV/dec.Experimental results reveal that the higher CO2 ER performance of Bi/Bi2 O3/NrGO-700 than that of Bi NPs supported on NrGO(Bi/NrGO)can be due to the partial reduction of Bi2 O3 NPs into Bi,which significantly increases undercoordinated active sites on Bi NPs surface,thus boosting its CO2 ER performance.Furthermore,a two-electrode device with Ir/C anode and Bi/Bi2 O3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO2 ER.展开更多
It is generally considered that the hydrogenation of CO2 is the critical bottleneck of the CO2 electroreduction.In this work,with the aid of density functional theory(DFT)calculations,the catalytic hydrogenation of CO...It is generally considered that the hydrogenation of CO2 is the critical bottleneck of the CO2 electroreduction.In this work,with the aid of density functional theory(DFT)calculations,the catalytic hydrogenation of CO2 molecules over Indium-doped SnP3 catalyst were systematically studied.Through doping with indium(In)atom,the energy barrier of CO2 protonation is reduced and OCHO*species could easily be generated.This is mainly due to the p orbital of In exhibits strong hybridization with the p orbital of O,indicating that there is a strong interaction between OCHO*and In-doped SnP3 catalyst.As a result,In-doped SnP3 possesses high-efficiency and high-selectivity for converting CO2 into HCOOH with a low limiting potential of-0.17 V.Our findings will offer theoretical guidance to CO2 electroreduction.展开更多
Exploring 3 D hybrid nanocarbons encapsulated with metal nanoparticles(NPs)are recently considered as emerging catalysts for boosting CO2 electroreduction reaction(CRR)under practical and economic limits.Herein,we rep...Exploring 3 D hybrid nanocarbons encapsulated with metal nanoparticles(NPs)are recently considered as emerging catalysts for boosting CO2 electroreduction reaction(CRR)under practical and economic limits.Herein,we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube(CNT)-encapsulated Ni NPs assembled on the surface of graphene(N/NiNPs@CNT/G)to efficiently convert CO2 into CO.In such 3 D hybrid,the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm,and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%.Thanks to unique CNT-encapsulated Ni NPs structure and N dopants,the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7%and large CO partial current density of 7.9 mA/cm2 at-0.7 V,which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts.Further,a low Tafel slope of 134 mV/dec,a turnover frequency of 387.3 CO/h at-0.9 V,and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G.Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO2 into CO with high current density.展开更多
Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalys...Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.展开更多
Electrochemical CO2 reduction reaction(CO2RR)to formate is economically viable considering the energy input and market value.Through learning nature,a series of chloroplast-like porous bismuth-based core–shell(CPBC)m...Electrochemical CO2 reduction reaction(CO2RR)to formate is economically viable considering the energy input and market value.Through learning nature,a series of chloroplast-like porous bismuth-based core–shell(CPBC)materials have been designed.In these materials,the porous carbon can enrich and transfer CO2 to the core–shell Bi@Bi2O3 in CO2 reduction process,during which Bi2O3 layer can be transformed into activated metastable layer to efficiently convert CO2 into formate and Bi can provide abundant electrons.Based on this,superior performances for most of important parameters in CO2 RR can be achieved and best of them,CPBC-1 presents remarkable Faradaic efficiency(FEformate>94%)over a wide potential range(-0.65 to-1.0 V)with high catalysis durability(>72 h).Noteworthy,its maximum energy efficiency is as high as 76.7%at-0.7 V,the highest one in reported bismuth-based materials.This work opens novel perspectives in designing nature-inspired CO2RR electrocatalysts.展开更多
Electrochemical conversion of CO2 into fuel has been regarded as a promising approach to achieve the global carbon cycle.Herein,we report an efficient cobalt catalyst with a unique flower-like morphology synthesized b...Electrochemical conversion of CO2 into fuel has been regarded as a promising approach to achieve the global carbon cycle.Herein,we report an efficient cobalt catalyst with a unique flower-like morphology synthesized by a green and facile hydrothermal method,in which n-butylamine is used as the capping agent.The resultant catalyst shows superior electrocatalytic activity toward CO2 electroreduction,which is highly selective for generating formate with a Faraday efficiency of 63.4%.Electrochemical analysis reveals that the oxide on the surface is essential for the electrocatalysis of the CO2 reduction reaction.Cyclic voltammograms further suggest that this catalyst is highly active for the oxidation of reduced product,and can thus be seen as a bifunctional catalyst.展开更多
Atomically dispersed metal-nitrogen sites-anchored carbon materials have been developed as effective catalysts for CO2 electroreduction(CO2 ER),but they still suffer from the imprecisely control of type and coordinati...Atomically dispersed metal-nitrogen sites-anchored carbon materials have been developed as effective catalysts for CO2 electroreduction(CO2 ER),but they still suffer from the imprecisely control of type and coordination number of N atoms bonded with central metal.Herein,we develop a family of single metal atom bonded by N atoms anchored on carbons(SAs-M-N-C,M=Fe,Co,Ni,Cu)for CO2 ER,which composed of accurate pyrrole-type M-N4 structures with isolated metal atom coordinated by four pyrrolic N atoms.Benefitting from atomically coordinated environment and specific selectivity of M-N4 centers,SAs-Ni-N-C exhibits superior CO2 ER performance with onset potential of-0.3 V,CO Faradaic efficiency(F.E.) of 98.5%at-0.7 V,along with low Tafel slope of 115 mV dec-1 and superior stability of 50 h,exceeding all the previously reported M-N-C electrocatalysts for CO2-to-CO conversion.Experimental results manifest that the different intrinsic activities of M-N4 structures in SAs-M-N-C result in the corresponding sequence of Ni> Fe> Cu> Co for CO2 ER performance.An integrated Zn-CO2 battery with Zn foil and SAs-Ni-N-C is constructed to simultaneously achieve CO2-to-CO conversion and electric energy output,which delivers a peak power density of 1.4 mW cm-2 and maximum CO F.E.of 93.3%.展开更多
Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especia...Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especially the existence and role of oxidized tin species under CO2 electroreduction conditions remain unclear.In this work,we provide strong evidence on the presence of oxidized tin species on both SnO_(2)and Sn during CO_(2)reduction via in situ surface‐enhanced Raman spectroscopy,while in different nature.Reactivity measurements show similar activity and selectivity to formate production on SnO_(2)and Sn catalysts.Combined analysis of Raman spectra and reactivity results suggests that Sn(IV)and Sn(II)oxide species are unlikely the catalytic species in CO_(2)electroreduction to formate.展开更多
Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts ...Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts for CO2 electroreduction(CO2ER).And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable.Here,In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition.In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous In2O3-x heterostructure(In/In2O3-x).In/In2O3-xacts as the real active phase with Faradaic efficiency of^89.2%for the formate,outperforming In(~67.5%).The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In2O3-xheterostructure.Impressively,formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In2O3-x||Ni2P two-electrode electrolyzer.展开更多
Copper-indium bimetallic catalysts with a dendritic structure are fabricated by a two-step electrodeposition method using a hydrogen evolution template for the CO2 electroreduction reaction(CO2RR).The dendritic Cu-In-...Copper-indium bimetallic catalysts with a dendritic structure are fabricated by a two-step electrodeposition method using a hydrogen evolution template for the CO2 electroreduction reaction(CO2RR).The dendritic Cu-In-30 catalyst electrodeposited for 30 min shows the highest specific surface area and exposes the most active sites,resulting in improved CO2RR activity.The dendritic Cu-In-30 catalyst exhibits distinctly higher formate partial current density(42.0 m A cm^-2)and Faradaic efficiency(87.4%)than those of the In-30 catalyst without the dendritic structure(the formate partial current density and Faradaic efficiency are 4.6 m A cm^-2 and 57.0%,respectively)at-0.85 V vs.reversible hydrogen electrode,ascribed to the increased specific surface area.The Cu-In-30 catalyst can maintain stable performance for 12 h during the CO2RR.In addition,the intrinsic current density of Cu-In-30 with the dendritic structure(4.8 m A cm^-2)is much higher than that of In-30 without the dendritic structure(2.1 m A cm^-2),indicating that the dendritic structure promotes the CO2RR,possibly due to additional coordination unsaturated atoms.展开更多
Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is...Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is likely the active phase for CO_2 reduction. We showed that the proton-electron transfer to adsorbed *CO_2 forming *OCHO, a key intermediate for producing HCOOH, is energetically more favorable than the formation of *COOH, justifying the selectivity trends observed on Sn-based electrocatalysts. With linear scaling relations, we propose the free formation energy of *CO_2 at the oxygen vacancy as the reactivity descriptor. By engineering the strain of the SnO(101) surface, the selectivity towards HCOOH can be further optimized at reduced overpotentials.展开更多
Among all CO2 electroreduction products,methane(CH4)and ethylene(C_(2)H_(4))are two typical and valuable hydrocarbon products which are formed in two different pathways:hydrogenation and dimerization reactions of the ...Among all CO2 electroreduction products,methane(CH4)and ethylene(C_(2)H_(4))are two typical and valuable hydrocarbon products which are formed in two different pathways:hydrogenation and dimerization reactions of the same CO intermediate.Theoretical studies show that the adsorption configurations of CO intermediate determine the reaction pathways towards CH4/C_(2)H_(4).However,it is challenging to experimentally control the CO adsorption configurations at the catalyst surface,and thus the hydrocarbon selectivity is still limited.Herein,we seek to synthesize two well-defined copper nanocatalysts with controllable surface structures.The two model catalysts exhibit a high hydrocarbon selectivity toward either CH4(83%)or C_(2)H_(4)(93%)under identical reduction conditions.Scanning transmission electron microscopy and X-ray absorption spectroscopy characterizations reveal the low-coordination Cu^(0)sites and local Cu^(0)/Cu^(+)sites of the two catalysts,respectively.CO-temperature programed desorption,in-situ attenuated total reflection Fourier transform infrared spectroscopy and density functional theory studies unveil that the bridge-adsorbed CO(CO_(B))on the low-coordination Cu^(0)sites is apt to be hydrogenated to CH4,whereas the bridge-adsorbed CO plus linear-adsorbed CO(CO_(B)+CO_(L))on the local Cu^(0)/Cu^(+)sites are apt to be coupled to C_(2)H_(4).Our findings pave a new way to design catalysts with controllable CO adsorption configurations for high hydrocarbon product selectivity.展开更多
基金support of the Natural Science Foundation of Zhejiang Province(No.LR16E080003)support of National Natural Science Foundation of China(Nos.21922811,51702284,21878270)+2 种基金Zhejiang Provincial Natural Science Foundation of China(No.LR19B060002)the Fundamental Research Funds for the Central Universitiesthe Startup Foundation for Hundred-Talent Program of Zhejiang University。
文摘Electrocatalytic CO2 reduction(CO2 ER)into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals,however,it still suffers from limited catalytic activity and poor selectivity.Herein,we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles(NPs)supported on nitrogen-doped reduced graphene oxide(Bi/Bi2 O3/NrGO)nanosheets prepared by a combined hydrothermal with calcination treatment.Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi2 O3,Bi/Bi2 O3/NrGO-700 hybrid displays a promoted CO2 ER catalytic performance and selectivity for formate production,as featured by a small onset potential of-0.5 V,a high current density of-18 mA/cm2,the maximum Faradaic efficiency of85%at-0.9 V,and a low Tafel slope of 166 mV/dec.Experimental results reveal that the higher CO2 ER performance of Bi/Bi2 O3/NrGO-700 than that of Bi NPs supported on NrGO(Bi/NrGO)can be due to the partial reduction of Bi2 O3 NPs into Bi,which significantly increases undercoordinated active sites on Bi NPs surface,thus boosting its CO2 ER performance.Furthermore,a two-electrode device with Ir/C anode and Bi/Bi2 O3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO2 ER.
基金supported by the National Natural Science Foundation of China(Nos.11675051,51302079,51702138)the Natural Science Foundation of Hunan Province(No.2017JJ1008)the Key Research and Development Program of Hunan Province of China(No.2018GK2031)。
文摘It is generally considered that the hydrogenation of CO2 is the critical bottleneck of the CO2 electroreduction.In this work,with the aid of density functional theory(DFT)calculations,the catalytic hydrogenation of CO2 molecules over Indium-doped SnP3 catalyst were systematically studied.Through doping with indium(In)atom,the energy barrier of CO2 protonation is reduced and OCHO*species could easily be generated.This is mainly due to the p orbital of In exhibits strong hybridization with the p orbital of O,indicating that there is a strong interaction between OCHO*and In-doped SnP3 catalyst.As a result,In-doped SnP3 possesses high-efficiency and high-selectivity for converting CO2 into HCOOH with a low limiting potential of-0.17 V.Our findings will offer theoretical guidance to CO2 electroreduction.
基金support of the National Natural Science of Fundation of China(Nos.51702284,21878271,21878270 and21961160742)Natural Science Foundation of Zhejiang Province(No.LR19B060002)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Startup Foundation for HundredTalent Program of Zhejiang University。
文摘Exploring 3 D hybrid nanocarbons encapsulated with metal nanoparticles(NPs)are recently considered as emerging catalysts for boosting CO2 electroreduction reaction(CRR)under practical and economic limits.Herein,we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube(CNT)-encapsulated Ni NPs assembled on the surface of graphene(N/NiNPs@CNT/G)to efficiently convert CO2 into CO.In such 3 D hybrid,the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm,and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%.Thanks to unique CNT-encapsulated Ni NPs structure and N dopants,the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7%and large CO partial current density of 7.9 mA/cm2 at-0.7 V,which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts.Further,a low Tafel slope of 134 mV/dec,a turnover frequency of 387.3 CO/h at-0.9 V,and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G.Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO2 into CO with high current density.
基金the National Key Research and Development Program of China(Nos.2017 YFA0206500 and 2018YFA0209103)the National Natural Science Foundation of China(Nos.21832003,21773111,21972061,51571110,and 21573107).The numerical calculations have been done on the computing facilities in the High Performance Computing Center(HPCC)of Nanjing University.
文摘Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.
基金financially supported by the National Natural Science Foundation of China(21622104,21871142 and 21901122)the Natural Science Foundation of Jiangsu Province of China(BK20171032)+3 种基金the Natural Science Research of Jiangsu Higher Education Institutions of China(17KJB150025 and 19KJB150011)Projects funded by China Postdoctoral Science Foundation(2018 M630572 and 2019 M651873)Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Foundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materials。
文摘Electrochemical CO2 reduction reaction(CO2RR)to formate is economically viable considering the energy input and market value.Through learning nature,a series of chloroplast-like porous bismuth-based core–shell(CPBC)materials have been designed.In these materials,the porous carbon can enrich and transfer CO2 to the core–shell Bi@Bi2O3 in CO2 reduction process,during which Bi2O3 layer can be transformed into activated metastable layer to efficiently convert CO2 into formate and Bi can provide abundant electrons.Based on this,superior performances for most of important parameters in CO2 RR can be achieved and best of them,CPBC-1 presents remarkable Faradaic efficiency(FEformate>94%)over a wide potential range(-0.65 to-1.0 V)with high catalysis durability(>72 h).Noteworthy,its maximum energy efficiency is as high as 76.7%at-0.7 V,the highest one in reported bismuth-based materials.This work opens novel perspectives in designing nature-inspired CO2RR electrocatalysts.
文摘Electrochemical conversion of CO2 into fuel has been regarded as a promising approach to achieve the global carbon cycle.Herein,we report an efficient cobalt catalyst with a unique flower-like morphology synthesized by a green and facile hydrothermal method,in which n-butylamine is used as the capping agent.The resultant catalyst shows superior electrocatalytic activity toward CO2 electroreduction,which is highly selective for generating formate with a Faraday efficiency of 63.4%.Electrochemical analysis reveals that the oxide on the surface is essential for the electrocatalysis of the CO2 reduction reaction.Cyclic voltammograms further suggest that this catalyst is highly active for the oxidation of reduced product,and can thus be seen as a bifunctional catalyst.
基金financial support from Zhejiang Province Basic Public Welfare Research Project(LGF19B070006)financial supports from National Natural Science Foundation of China(21922811,21878270,51702284,21961160742)+2 种基金Zhejiang Provincial Natural Science Foundation of China(LR19B060002)supported by the Fundamental Research Funds for the Central Universitiesthe Startup Foundation for Hundred-Talent Program of Zhejiang University.
文摘Atomically dispersed metal-nitrogen sites-anchored carbon materials have been developed as effective catalysts for CO2 electroreduction(CO2 ER),but they still suffer from the imprecisely control of type and coordination number of N atoms bonded with central metal.Herein,we develop a family of single metal atom bonded by N atoms anchored on carbons(SAs-M-N-C,M=Fe,Co,Ni,Cu)for CO2 ER,which composed of accurate pyrrole-type M-N4 structures with isolated metal atom coordinated by four pyrrolic N atoms.Benefitting from atomically coordinated environment and specific selectivity of M-N4 centers,SAs-Ni-N-C exhibits superior CO2 ER performance with onset potential of-0.3 V,CO Faradaic efficiency(F.E.) of 98.5%at-0.7 V,along with low Tafel slope of 115 mV dec-1 and superior stability of 50 h,exceeding all the previously reported M-N-C electrocatalysts for CO2-to-CO conversion.Experimental results manifest that the different intrinsic activities of M-N4 structures in SAs-M-N-C result in the corresponding sequence of Ni> Fe> Cu> Co for CO2 ER performance.An integrated Zn-CO2 battery with Zn foil and SAs-Ni-N-C is constructed to simultaneously achieve CO2-to-CO conversion and electric energy output,which delivers a peak power density of 1.4 mW cm-2 and maximum CO F.E.of 93.3%.
文摘Electrochemical CO_(2)reduction to formate is a promising approach to store renewable electricity and utilize CO_(2).Tin oxide catalysts are efficient catalysts for this process,while the mechanisms underneath,especially the existence and role of oxidized tin species under CO2 electroreduction conditions remain unclear.In this work,we provide strong evidence on the presence of oxidized tin species on both SnO_(2)and Sn during CO_(2)reduction via in situ surface‐enhanced Raman spectroscopy,while in different nature.Reactivity measurements show similar activity and selectivity to formate production on SnO_(2)and Sn catalysts.Combined analysis of Raman spectra and reactivity results suggests that Sn(IV)and Sn(II)oxide species are unlikely the catalytic species in CO_(2)electroreduction to formate.
基金the National Natural Science Foundation of China (21871206 and 21701122)。
文摘Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts for CO2 electroreduction(CO2ER).And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable.Here,In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition.In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous In2O3-x heterostructure(In/In2O3-x).In/In2O3-xacts as the real active phase with Faradaic efficiency of^89.2%for the formate,outperforming In(~67.5%).The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In2O3-xheterostructure.Impressively,formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In2O3-x||Ni2P two-electrode electrolyzer.
文摘Copper-indium bimetallic catalysts with a dendritic structure are fabricated by a two-step electrodeposition method using a hydrogen evolution template for the CO2 electroreduction reaction(CO2RR).The dendritic Cu-In-30 catalyst electrodeposited for 30 min shows the highest specific surface area and exposes the most active sites,resulting in improved CO2RR activity.The dendritic Cu-In-30 catalyst exhibits distinctly higher formate partial current density(42.0 m A cm^-2)and Faradaic efficiency(87.4%)than those of the In-30 catalyst without the dendritic structure(the formate partial current density and Faradaic efficiency are 4.6 m A cm^-2 and 57.0%,respectively)at-0.85 V vs.reversible hydrogen electrode,ascribed to the increased specific surface area.The Cu-In-30 catalyst can maintain stable performance for 12 h during the CO2RR.In addition,the intrinsic current density of Cu-In-30 with the dendritic structure(4.8 m A cm^-2)is much higher than that of In-30 without the dendritic structure(2.1 m A cm^-2),indicating that the dendritic structure promotes the CO2RR,possibly due to additional coordination unsaturated atoms.
基金financial support from the American Chemical Society Petroleum Research Fund (ACS PRF 55581-DNI5)the Institute for Critical Technology and Applied Science (ICTAS-J0663175)the NSF CBET Catalysis and Biocatalysis Program (CBET-1604984)
文摘Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is likely the active phase for CO_2 reduction. We showed that the proton-electron transfer to adsorbed *CO_2 forming *OCHO, a key intermediate for producing HCOOH, is energetically more favorable than the formation of *COOH, justifying the selectivity trends observed on Sn-based electrocatalysts. With linear scaling relations, we propose the free formation energy of *CO_2 at the oxygen vacancy as the reactivity descriptor. By engineering the strain of the SnO(101) surface, the selectivity towards HCOOH can be further optimized at reduced overpotentials.
基金supported by the National Natural Science Foundation of China (21875042)Shanghai Science and Technology Committee (18QA1400800)+1 种基金the Program of Eastern Scholar at Shanghai Institutions and Yanchang Petroleum Groupsupported by the Frontier Research Center for Materials Structure, School of Materials Science and Engineering of Shanghai Jiao Tong University
文摘Among all CO2 electroreduction products,methane(CH4)and ethylene(C_(2)H_(4))are two typical and valuable hydrocarbon products which are formed in two different pathways:hydrogenation and dimerization reactions of the same CO intermediate.Theoretical studies show that the adsorption configurations of CO intermediate determine the reaction pathways towards CH4/C_(2)H_(4).However,it is challenging to experimentally control the CO adsorption configurations at the catalyst surface,and thus the hydrocarbon selectivity is still limited.Herein,we seek to synthesize two well-defined copper nanocatalysts with controllable surface structures.The two model catalysts exhibit a high hydrocarbon selectivity toward either CH4(83%)or C_(2)H_(4)(93%)under identical reduction conditions.Scanning transmission electron microscopy and X-ray absorption spectroscopy characterizations reveal the low-coordination Cu^(0)sites and local Cu^(0)/Cu^(+)sites of the two catalysts,respectively.CO-temperature programed desorption,in-situ attenuated total reflection Fourier transform infrared spectroscopy and density functional theory studies unveil that the bridge-adsorbed CO(CO_(B))on the low-coordination Cu^(0)sites is apt to be hydrogenated to CH4,whereas the bridge-adsorbed CO plus linear-adsorbed CO(CO_(B)+CO_(L))on the local Cu^(0)/Cu^(+)sites are apt to be coupled to C_(2)H_(4).Our findings pave a new way to design catalysts with controllable CO adsorption configurations for high hydrocarbon product selectivity.
